Alcoholic liver disease if the result of alcohol-induced hepatotoxicity coupled with impaired hepatic regenerative capacity. In animal models, acute or chronic exposure to ethanol impairs liver regeneration following partial hepatectomy or chemically induced liver injury, but the mechanisms by which ethanol inhibits liver regeneration are still unknown. Recent evidence obtained in 'knock-out' mice deficient in interleukin-6 (il-6) indicates that activation by IL-6 of the signal transducer and activation of transcription protein 3 (Stat3) is a critical step in liver regeneration. Preliminary experiments have shown that acute treatment with ethanol can block the activation of Stat3 in the rat liver, induced by IL- 6 in vitro or by partial hepatectomy in vivo. These findings suggest that the anti-regenerative effects of ethanol are mediated, at least in part, through blocking IL-6 induced Stat3 activation. The mechanism by which ethanol inhibits IL-6-induced Stat3 activation will be explored by analyzing the effects of acute ethanol treatment on the IL-6-induced signal transduction cascade, including the interaction of IL-6 with its receptor, the tyrosine phosphorylation of the gp130 protein and IL-6- induced activation of the JAK kinases. The effects of chronic ethanol on Stat3 activation induced by IL-6 or partial hepatectomy will be explored in rats maintained on a ethanol-containing liquid diet. Identification of the IL-signaling pathway modulated by ethanol will not only enhance our understanding of the pathogenesis of alcoholic-induced liver disease but may also shed light on the effects of ethanol on signal systems in other tissues such as the brain.